From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11E17C10F12 for ; Mon, 15 Apr 2019 18:51:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D50322073F for ; Mon, 15 Apr 2019 18:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555354287; bh=O8ghSaqomER1TdRDCFfbm6Wh9mkw0U4JbgVizdDs5PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JOkRt/IDjZ0sRpSmLHNrwyY+RoDygabWo7NBKcWxL/SjLWWCezv6Oso9v8TmKe/3n 0CFECGGIzk96vsd4s14NEKb31udVnIdoAlrbYHVPDHV4TYdZsOwkLTc1TQQAYfadcV uQB2B1LySh3cLuaxEoPyWQj8bM0yZedgtH4e6ihk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728438AbfDOSpo (ORCPT ); Mon, 15 Apr 2019 14:45:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:48182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728393AbfDOSpn (ORCPT ); Mon, 15 Apr 2019 14:45:43 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C17B2073F; Mon, 15 Apr 2019 18:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555353942; bh=O8ghSaqomER1TdRDCFfbm6Wh9mkw0U4JbgVizdDs5PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lFqCwSdQ5PqYZ3sDVtwu0XoV2rXvA40BK5IoqWV6f+9sxgSjzMAC3vVhHTWfUl/mz Dz29+PUhbzAMVxZvPYbFtZRTivF47NTdisukkTf9TEF4onmKRel+qR4hdcFy3fawd1 Rd+3bCdriY1IUHKK8owToR0AWLQGT0h9xtGCF64I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Neuling , Nicholas Piggin , Christophe Leroy , Michael Ellerman , Sasha Levin Subject: [PATCH 4.9 13/76] powerpc: Avoid code patching freed init sections Date: Mon, 15 Apr 2019 20:43:37 +0200 Message-Id: <20190415183711.514716690@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190415183707.712011689@linuxfoundation.org> References: <20190415183707.712011689@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3 upstream. This stops us from doing code patching in init sections after they've been freed. In this chain: kvm_guest_init() -> kvm_use_magic_page() -> fault_in_pages_readable() -> __get_user() -> __get_user_nocheck() -> barrier_nospec(); We have a code patching location at barrier_nospec() and kvm_guest_init() is an init function. This whole chain gets inlined, so when we free the init section (hence kvm_guest_init()), this code goes away and hence should no longer be patched. We seen this as userspace memory corruption when using a memory checker while doing partition migration testing on powervm (this starts the code patching post migration via /sys/kernel/mobility/migration). In theory, it could also happen when using /sys/kernel/debug/powerpc/barrier_nospec. Cc: stable@vger.kernel.org # 4.13+ Signed-off-by: Michael Neuling Reviewed-by: Nicholas Piggin Reviewed-by: Christophe Leroy Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/include/asm/setup.h | 1 + arch/powerpc/lib/code-patching.c | 8 ++++++++ arch/powerpc/mm/mem.c | 2 ++ 3 files changed, 11 insertions(+) diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h index 703ddf752516..709f4e739ae8 100644 --- a/arch/powerpc/include/asm/setup.h +++ b/arch/powerpc/include/asm/setup.h @@ -8,6 +8,7 @@ extern void ppc_printk_progress(char *s, unsigned short hex); extern unsigned int rtas_data; extern unsigned long long memory_limit; +extern bool init_mem_is_free; extern unsigned long klimit; extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask); diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 753d591f1b52..c77c486fbf24 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -14,12 +14,20 @@ #include #include #include +#include +#include int patch_instruction(unsigned int *addr, unsigned int instr) { int err; + /* Make sure we aren't patching a freed init section */ + if (init_mem_is_free && init_section_contains(addr, 4)) { + pr_debug("Skipping init section patching addr: 0x%px\n", addr); + return 0; + } + __put_user_size(instr, addr, 4, err); if (err) return err; diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 5f844337de21..1e93dbc88e80 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -62,6 +62,7 @@ #endif unsigned long long memory_limit; +bool init_mem_is_free; #ifdef CONFIG_HIGHMEM pte_t *kmap_pte; @@ -396,6 +397,7 @@ void __init mem_init(void) void free_initmem(void) { ppc_md.progress = ppc_printk_progress; + init_mem_is_free = true; free_initmem_default(POISON_FREE_INITMEM); } -- 2.19.1